Dome cameras are widely used in various applications for capturing images of a scene. One particular application exists in the field of surveillance. The dome of the camera advantageously protects components of the camera from outside particles and liquids. Furthermore, the dome can assist in concealing the orientation of the lens of the camera. This concealment reduces the feeling of intrusion for people present near the camera. Typically, the optical module of a dome camera is pan, rotated and tilted to aim the optical module in a direction for a desired field of view.
Typically the camera module is able to be tilted between zero and ninety degrees. The tilting mechanism is simple for such short adjustments. However, the optical module in a domed camera has to allow panning for at least 360 degrees in order to ensure full coverage, but not much more than 360 degrees in order to ensure that the wires connecting to the optical module are not stressed by the twisting as a result of the optical module being pan rotated.
A yoke 1920 in accordance with the prior art is shown in FIG. 19. The yoke 1920 includes a first arm 1925 and a second arm 1930. The first arm 1925 has a first draft surface 1935 and the second arm 1930 has a second draft surface 1940. The yoke 1920 has the two arms 1925, 1930 that extend outwards for some distance and then extend upwards. The upwards extending parts are the draft surfaces 1935, 1940 each containing pass-throughs for screw bosses which acts as an axle for tilt rotation of an optical module, and track slots wherein a locking thumb screw rides. One locking thumb screw is sufficient to lock the yoke 1920 from tilt rotating, but two locking thumb screws may also be used, one on each draft surface 1935, 1940.
To manufacture this yoke 1920 part, the pass-throughs are created by a slider in a mold tool, where the exterior surface on the yoke 1920 is normal to movement of the slider direction 1945. The inside surface is created on the core (core direction 1950) of the tool, this necessitates a draft 1955 on the inside surface of each arm 1925, 1930 of the yoke 1920 to allow the part to be removed from the tool. The draft 1955 is, for example, a 1.5 degree angle on the inside surface of the draft surfaces 1935, 1940 to make the inside surfaces of the yoke 1920 angled slight outward from the vertical, while leaving the exterior surfaces of the draft surfaces 1935, 1940 parallel to each other. The draft 1955 creates a non-uniform thickness for the clamping action of the locking thumb screw, but which may too easily allow the optical module to tilt in one direction with little force.